An electron precipitation event has been investigated with bremsstrahlung X ray mapping data taken from two satellites and with ground-based riometer and magnetometer data. The event occurred near 2300 UT on June 27, 1982, in the vicinity of South Pole Station, which was in the dusk-midnight local time sector. The main precipitation was associated with a poleward-moving westward electrojet and produced the largest riometer absorption (exceeding 10 d at 30 MHz) recorded during 1982 at that station. The feature examined in detail here is an intense spike of ~10 s duration and limited spatial extent that occcurred as a short-lived eastward ionospheric current developed equatorward of the west-ward electrojet. At the time of the spike, two sensors on the P78-1 satellite essentially simultaneously measured X rays from the region viewed by the ground-based instruments. Movement of the spike precipitation region toward the pole was indicated by the measurements. From ratios of the riometer absorption at different frequencies it is concluded that the spike precipitation region is consistent with a strip of width ~25 km and length greater than 100 km. The total flux of the precipitating electrons in the spike was ~4¿1023el/s(~2¿1016 ergs/s) with an e-fold energy of ~40 keV. The fluxes and energy spectra of X rays emitted from a large area, as measured by the spacecraft, were about the same before and after the spike. However, following the spike there was a pronounced decrease in riometer absorption, which suggests a movement of the main precipitation region away from the south pole at that time.